432 research outputs found
The electron-nucleon cross section in reactions
We examine commonly used approaches to deal with the scattering of electrons
from a bound nucleon. Several prescriptions are shown to be related by gauge
transformations. Nevertheless, due to current non-conservation, they yield
different results. These differences reflect the size of the uncertainty that
persists in the interpretation of experiments.Comment: 6 pp (10 in preprint form), ReVTeX, (+ 4 figures, uuencoded
Nuclear currents based on the integral form of the continuity equation
We present an approach to obtain new forms of the nuclear electromagnetic
current, which is based on an integral form of the continuity equation. The
procedure can be used to restore current conservation in model calculations in
which the continuity equation is not verified. Besides, it provides, as a
particular result, the so-called Siegert's form of the nuclear current, first
obtained by Friar and Fallieros by extending Siegert's theorem to arbitrary
values of the momentum transfer. The new currents are explicitly conserved and
permit a straightforward analysis of their behavior at both low and high
momentum transfers. The results are illustrated with a simple nuclear model
which includes a harmonic oscillator mean potential.Comment: 19 pages, revtex, plus 2 PS figure
Are Hospital Efficiency and Quality of Care Affordable without External Revenue?
This qualitative study explored strategies academic research hospital administrators in Ontario, Canada, apply to generate nongovernment revenue to remain sustainable. The participants in the study consisted of senior-level academic research hospital executives with extensive experience in the subject area from major academic research hospitals, ranking the hospitals from highest to lowest in revenue generation. From this study, five themes emerged: working within the fiscal reality, the impact of the political environment, the focus on the mission, nongovernment revenue generation, and opportunities for the Ontario academic research hospitals. Findings from this study may contribute to discussions on implementing change by encouraging hospital executives to adopt a more coordinated and consistent approach to generating nongovernment revenue to support the mission of their hospitals
Deep-ultraviolet cavity ringdown spectroscopy
The sensitive optical detection technique of cavity ringdown spectroscopy is extended to the wavelength range 197-204 nm. A novel design narrowband Fourier-transform-limited laser is used, and the technique is applied to gas-phase extinction measurements in CO2, SF6, and O-2. Further demonstration of the system capabilities is given in high-resolution recordings of the Schumann-Runge (0, 0), (1, 0), and (2, 0) bands in O-2. (C) 2004 Optical Society of America
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Concrete containment aging study
In 1989, IAEA initiated a pilot study on the management of aging of nuclear power plant components. The Phase I and II studies of concrete containment are discussed. With the data base, plant owners will be able to review and enhance their existing programs. IAEA will analyze data provided by participating plants and the report is scheduled to be released by late 1994 (final report release mid-1995)
The off-shell electromagnetic form factors of pions and kaons in chiral perturbation theory
The off-shell electromagnetic vertex of a (pseudo-) scalar particle contains,
in general, two form factors F and G which depend, in addition to the squared
momentum transfer, on the invariant masses associated with the initial and
final legs of the vertex. Chiral perturbation theory to one loop is used to
calculate the off-shell form factors of pions and kaons. The formalism of
Gasser and Leutwyler, which was previously used to calculate the on-shell limit
of the form factor F, is extended to accommodate the most general form for
off-shell Green's functions in the pseudoscalar meson sector. We find that
chiral symmetry predicts that the form factors F of the charged pions and kaons
go off-shell in the same way, i.e., the off-shell slope at the real photon
point is given by the same new phenomenological constant .
Furthermore, it is shown that at order the form factor F of the
does not show any off-shell dependence. The form factors G are all related to
the form factors F in the correct fashion as required by the Ward-Takahashi
identity. Numerical results for different off-shell kinematics are presented.Comment: TRIUMF preprint TRI-PP-94-4, 25 pages in LaTeX + 10 figures
(uufile'd, compressed PostScript file appended at end, hardcopy available
from authors
Transverse QCD Dynamics Near the Light Cone
Starting from the QCD Hamiltonian in near-light cone coordinates, we study
the dynamics of the gluonic zero modes. Euclidean 2+1 dimensional lattice
simulations show that the gap at strong coupling vanishes at intermediate
coupling. This result opens the possibility to synchronize the continuum limit
with the approach to the light cone.Comment: 15 pages, LaTeX, 3 figures (7 PS files
QCD near the Light Cone
Starting from the QCD Lagrangian, we present the QCD Hamiltonian for near
light cone coordinates. We study the dynamics of the gluonic zero modes of this
Hamiltonian. The strong coupling solutions serve as a basis for the complete
problem. We discuss the importance of zero modes for the confinement mechanism.Comment: 32 pages, ReVTeX, 2 Encapsulated PostScript figure
The Role of Final State Interactions in Quasielastic Fe Reactions at large
A relativistic finite nucleus calculation using a Dirac optical potential is
used to investigate the importance of final state interactions [FSI] at large
momentum transfers in inclusive quasielastic electronuclear reactions. The
optical potential is derived from first-order multiple scattering theory and
then is used to calculate the FSI in a nonspectral Green's function doorway
approach. At intermediate momentum transfers excellent predictions of the
quasielastic Fe experimental data for the longitudinal response
function are obtained. In comparisons with recent measurements at ~GeV/c the theoretical calculations of give good agreement for
the quasielastic peak shape and amplitude, but place the position of the peak
at an energy transfer of about ~MeV higher than the data.Comment: 13 pages typeset using revtex 3.0 with 6 postscript figures in
accompanying uuencoded file; submitted to Phys. Rev.
A Gauge Invariant Unitary Theory for Pion Photoproduction
A covariant, unitary and gauge invariant theory for pion photoproduction on a
single nucleon is presented. To achieve gauge invariance at the operator level
one needs to include both the and thresholds. The final
amplitude can be written in terms of a distorted wave in the final
channel provided one includes additional diagrams to the standard Born term in
which the photon is coupled to the final state pion and nucleon. These
additional diagrams are required in order to satisfy gauge invariance.Comment: 4 pages, LaTeX, 1 figure as a separate uuencoded compressed tar fil
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